Gut microbiota dysbiosis in rheumatoid arthritis: a systematic review and meta-analysis

Background: Rheumatoid arthritis (RA) is an autoimmune joint disease with systemic manifestations. Emerging evidence implicates the gut microbiota in the pathophysiology of RA. However, the specific changes in the gut microbiota in RA patients remain poorly understood. Methods: We conducted a comprehensive search of PubMed, EMBASE, Web of Science, Cochrane Library, MEDLINE, Wanfang, VIP, CBM, and CNKI from the time the databases were created until October, 2023. To evaluate changes in α-diversity and the abundance of certain microbiota families in RA, standardized mean difference (SMD) and 95% confidence interval (CI) calculations were made. Results: Firstly, we evaluated the changes in α-diversity of gut microbes in patients with RA compared to healthy controls. Our analysis of 18 studies revealed a significant decrease in richness and evenness among RA patients. Importantly, the subgroup analysis suggested the decrease in α-diversity was more significant in treatment naïve patients rather than those who received anti-rheumatic medication. Additionally, in the subgroup analysis of 316 patients stratified by baseline disease activity, no significant differences in α-diversity were detected between groups. Discussion: Our analysis further evidence of altered α-diversity and the relative abundance of specific bacteria in RA. These findings contribute to our understanding of the role of gut microbiota dysbiosis in the pathogenesis of RA. Further research is warranted to elucidate the underlying mechanisms and explore the potential therapeutic implications of targeting the gut microbiota in RA management.